References of "Job, Nathalie"
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See detailAdsorption du bleu de méthylène sur des xérogels de carbone activés
Páez Martínez, Carlos ULg; Contreras, Soledad; Léonard, Angélique ULg et al

Poster (2012, October)

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See detailResorcinol-formaldehyde carbon xerogels as lithium-ion battery anode materials: influence of porosity on capacity and cycling behaviour
Piedboeuf, Marie-Laure ULg; Léonard, Alexandre ULg; Khomenko, Volodymyr et al

Poster (2012, July 05)

Carbon xerogels are promising candidates in the development of new high performance C-based anode materials for Li-ion batteries. Indeed, their specific capacities widely exceed that of conventional ... [more ▼]

Carbon xerogels are promising candidates in the development of new high performance C-based anode materials for Li-ion batteries. Indeed, their specific capacities widely exceed that of conventional graphitic structures, and they can be intercalated/deintercalated in a low-cost electrolyte based on propylene carbonate (PC), which has an excellent conductivity at low temperatures. In addition, such carbonaceous materials show very small changes of volume during the charge/discharge, providing a long cycle life of such an anode. Nevertheless, hard carbons also exhibit quite high irreversible capacity losses due to their intrinsic high microporosity and, compared to graphite, a poor rate performance related to slow diffusion of Li in the internal structure[1]. To reduce these disadvantages, the structural and textural characteristics need to be carefully controlled. Porous carbon xerogels can easily be prepared from resorcinol-formaldehyde aqueous mixtures, which are polymerized, dried and pyrolysed. The porosity of these xerogels is mainly governed by the pH of the precursor solution as well as by the drying procedure. Globally, these materials are composed of microporous nodules delimiting meso- or macroporous voids, the size of which is adjusted via the synthesis pH. Too a high microporosity can induce considerable irreversible capacity losses and too small mesopores may hinder the proper chemical diffusion of lithium ions within a bulk electrode material. The latter is often a rate-limiting step and optimized transport pathways could be provided by creating large mesopores or even macropores within the microporous carbon [3]. Here we report on the preliminary electrochemical characterization of porous carbon xerogels prepared by vacuum drying procedure. By adjusting the pH of the precursor solution, the materials obtained develop low to high values of specific surface areas and exhibit homogeneous pore sizes that range from several microns to several nanometers. The electrochemical performance of these materials as electrode compounds was tested by galvanostatic charge-discharge of 16-mm disc electrodes assembled in CR2016 coin cells or of 13-mm disc electrodes in home-made Swagelok-type cells. The first results show that all the samples show quite a high irreversible capacity during the first cycle; this irreversible capacity is proportional to the specific surface area. Its value nevertheless remains quite low for the low-surface area macroporous sample. The latter also shows the best reversible capacity after the second cycle, with values approaching that of commonly used graphite. For example, when cycled at a rate of C/20 for 10 cycles, this sample showed a capacity of 320 mAh/g; the value was kept at 200 mAh/g when increasing the rate up to C/5. The long-term cycling performance was investigated by cycling the anodes at C/20 and C/5. Again, the macroporous sample behaves best, with superior capacity retention and invariable discharge capacity of ~175 mAh/g after more than 100 cycles. The electrochemical properties of carbon xerogels was evaluated in the conditions which are used typically for graphite (cycles in the potentials range from 0.003 to 1.5 V vs. Li+/Li). A higher reversible capacity of 400 mAh/g could be obtained for the macroporous sample using a discharge with plating of Li as described in [4], but this method could not be accepted in the case of Lithium-ion batteries. These first results show that carbon xerogels are very promising candidates as anode materials for Li batteries, providing the textural characteristics are carefully controlled. The ongoing work is dealing with the establishment of possible relationships between textural features and electrochemical performance in order to shed light on the requirements that will dictate the best synthesis procedures. References: [1] T. Tran, B. Yebka, X. Song, G. Nazri, K. Kinoshita and D. Curtis, J. Power Sources, 85, 269, 2000. [2] N. Job, A. Théry, R. Pirard, J. Marien, L. Kocon, J.-N. Rouzaud, F. Béguin and J.-P. Pirard, Carbon 43, 2481, 2005. [3] F. Cheng, Z. Tao, J. Liang, and J. Chen, Chem. Mater., 20, 667, 2008. [4] W. Xing, J. S. Xue, J.R. Dahn, J. Electrochem. Soc, 143, 3046, 1996. [less ▲]

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See detailSynthesis and characterization of porous carbon xerogels and ordered mesoporous carbons for anode materials in Li-based batteries
Léonard, Alexandre ULg; Pirard, Jean-Paul ULg; Job, Nathalie ULg

in Fagadar-Cosma, Eugenia (Ed.) Insights into novel solid materials, their recyclability and integration into Li polymer batteries for EVs. Future research directions in this field.:Book of abstracts (2012, July 04)

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See detailResorcinol-formaldehyde carbon xerogels as lithium-ion battery anode materials: influence of porosity on capacity and cycling behaviour
Léonard, Alexandre ULg; Piedboeuf, Marie-Laure ULg; Khomenko, Volodymyr et al

in Fagadar-Cosma, Eugenia (Ed.) Insights into novel solid materials, their recyclability and integration into Li polymer batteries for EVs. Future research directions in this field.:Book of abstracts (2012, July)

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See detailLife cycle assessment of carbon xerogels
Melon, Raphaëlle ULg; Renzoni, Roberto ULg; Léonard, Alexandre ULg et al

in Fagadar-Cosma, Eugenia (Ed.) Book of abstracts - Advanced Workshop - Insights into novel solid materials, their recyclability and integration into Li polymer batteries for EVs (2012, July)

In the framework of the SOMABAT European project, a life cycle assessment applied to the production of 1 kg of carbon xerogels was carried out by comparing three drying technologies (vacuum, microwave and ... [more ▼]

In the framework of the SOMABAT European project, a life cycle assessment applied to the production of 1 kg of carbon xerogels was carried out by comparing three drying technologies (vacuum, microwave and convective drying). These carbon materials with controlled texture are thought to be used as active material at the anode side of Li-polymer battery. [less ▲]

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See detailContinuous synthesis of porous carbon xerogel beads.
Eskenazi, David ULg; Kreit, Patrick ULg; Compère, Philippe ULg et al

in Proceedings of the International Carbon Conference 2012 (2012, June 17)

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See detailDépôt de nanoparticules par voie humide
Job, Nathalie ULg

Conference (2012, June 10)

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See detailComment diminuer la quantité de platine dans les piles à combustible ?
Laurent-Brocq, M.; Caldarella, Giuseppe ULg; Job, Nathalie ULg et al

Poster (2012, May 20)

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See detailResorcinol-formaldehyde carbon xerogels as lithium-ion battery anode materials: influence of porosity on capacity and cycling behaviour
Léonard, Alexandre ULg; Piedboeuf, Marie-Laure ULg; Khomenko, Volodymyr et al

in Proceedings of the International Carbon Conference 2012 (2012)

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See detailInfluence of the carbon texture of platinum/carbon aerogel electrocatalysts on their behaviour in a Proton Exchange Membrane Fuel Cell cathode
Ouattara-Brigaudet, M.; Berthon-Fabry, S.; Beauger, C. et al

in International Journal of Hydrogen Energy (2012), 37

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See detailUse of X-ray microtomography to study the homogeneity of carbon nanotube aqueous suspensions and carbon nanotube/polymer composites
Haghgoo, M.; Plougonven, Erwan ULg; Yousefi, Ali Akbar et al

in Carbon (2012), 50(4), 1703-1706

X-ray microtomography was used to study the stability and homogeneity of concentrated carbon nanotube (CNT) aqueous suspensions and CNT/resorcinol–formaldehyde gel composites. Various CNT distribution ... [more ▼]

X-ray microtomography was used to study the stability and homogeneity of concentrated carbon nanotube (CNT) aqueous suspensions and CNT/resorcinol–formaldehyde gel composites. Various CNT distribution states were achieved by modifying the CNT concentration, sonication time and resting time. X-ray microtomography is able to discriminate between zones with different CNT concentration levels and can be used as a non-destructive and fast tool to characterize the homogeneity of suspensions and composite systems at the micron scale. [less ▲]

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See detailCatalysts - special issue 'Aerogel catalysts'
Job, Nathalie ULg; Ioannides, Theophilos

Book published by MDPI (2012)

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See detailEffect of CO2 activation of carbon xerogels on the adsorption of methylene blue
Páez Martínez, Carlos ULg; Contreras, M. S.; Léonard, Angélique ULg et al

in Adsorption (2012), 18(3-4), 199-211

The effect of physical activation with CO2 of carbon xerogels, synthesized by pyrolysis of a resorcinolformaldehyde aqueous gel, on the adsorption capacities of Methylene Blue (MB) was studied. The ... [more ▼]

The effect of physical activation with CO2 of carbon xerogels, synthesized by pyrolysis of a resorcinolformaldehyde aqueous gel, on the adsorption capacities of Methylene Blue (MB) was studied. The activation with CO2 lead to carbon materials with micropore volumes ranging from 0.28 to 0.98 cm³/g -1 C. MB-adsorption isotherm studies showed that the increase of micropore volume and corresponding surface area led to: (i) a significant improvement in the capacity of MB-adsorption at monolayer coverage, from 212 to 714 mgg -1 C, and (ii) an increase of the binding energy related to Langmuir isotherm constant up to 45 times greater than those of commercial microporous activated carbons used as reference (NORIT R2030, CALGON BPL and CALGON NC35). It is proposed that the increase of the binding energy results from chemical cleaning of the O-groups onto carbon surface as a consequence of CO2-activation, increasing the π-π interaction between MB and graphene layers of the carbon xerogels. Finally, a series of batch kinetics were performed to investigate the effect of CO2-activation conditions on the mechanism of MB-adsorption. Experimental data were fitted using pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. From pseudo-second-order kinetic model, one observes an increase in the initial rate of MB-adsorption from 0.019 to 0.0565 min -1, by increasing the specific surface area from 630 to 2180 m²/g -1 C via CO2-activation. Depending on the activation degree of the carbons, two different mechanisms control the MB-adsorption rate: (i) at low activation degree, the intraparticle diffusion is the rate-limiting phenomenon, whereas (ii) at high activation degree, the reactions occurring at the solid/liquid interface are the rate-limiting steps. © 2012 Springer Science+Business Media, LLC. [less ▲]

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See detailAdsorption of methylene blue on activated carbon xerogels
Páez Martínez, Carlos ULg; Contreras, Maria Soledad; Léonard, Angélique ULg et al

Poster (2011, November 30)

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See detailLife cycle assessment of carbon xerogels
Melon, Raphaëlle ULg; Renzoni, Roberto ULg; Léonard, Alexandre ULg et al

Poster (2011, November 03)

Detailed reference viewed: 19 (6 ULg)